Provided by: ifupdown-extra_0.28_all bug


       network-test - check the network and test if everything is fine




       The  network-test  program will test your system's network configuration using basic tests
       and providing both information (INFO), warnings (WARN) and possible errors (ERR) based  on
       the results of these tests.  It will check and report on:
              * Status of the network interfaces of the system including: link status,
               IP addressing and number of transmitted packets and error rates.

              * Accessibility to configured routes to external networks,
                including the default network route, checking the routers configured
                to give access to the network

              * Proper host resolution, testing DNS resolution against a known host.

              *  Proper network connectivity, testing reachability of remote hosts using ICMP and
              simulating a web connections to a remote web server (the web server  used  for  the
              tests can be configured through the environment, see below)

       The program does not need special privileges to run as it does not do any system change.

       However, the behaviour of the program when running as an unprivileged user is not the same
       as running as  system  administrator  (i.e.  root).  If  the  program  is  run  as  system
       administrator it will try to run some tools that are only available to it to speed up some
       of the tests.

       The program relies on the use of ip, netstat, ifconfig, arp and  (when  running  as  root)
       ethtool  or  mii-tool,  to  obtain information about the system's networking configuration
       (status of available interfaces and configured network routes). It also  uses  ping,  host
       and  nc  (netcat)  to  do  tests  of the network connectivity and ensure that the host can
       connect to the Internet.


       The program will, by default, check and its associated web server.  If  you
       want to use a different check host you can setup the environment as follows:

              The name of a host to use when testing DNS resolution.  By default ''

              The  CHECK_HOST  ´s  IP  address.   By  default  defined  with the following value:

              The web server to use for testing purposes when testing network  connectivity.   By
              default it will use ''

              The  web  server  port  of  server CHECK_WEB_HOST that will be used for testing. By
              default it will use TCP port 80..

              A web service to test network connectivity by downloading some content. By  default
              it will use ''

              The MD5sum value of the content being checked.

              A  web service used to determine the system's public IP address. By default it will
              use ''


       The program will exit with error (1) if any of the network checks fail.


       This program does not have super cow powers so it is unable to fix the errors  by  itself.
       It  is also unable to detect if the network is failing due to a local firewall policy been
       in place so make sure you check your system logs with dmesg (1) to detect if some  of  the
       active tests are being dropped due to your local firewall.

       Other known issues that might make the program not work reliable are:

              *  IPv6:  The  program  does not yet explicitly handle IPv6 only hosts, some of the
              tests might be biased towards IPv4 and might fail in IPv6 environments.

              * Proxies: The program does not check network connectivity for hosts  that  connect
              through  the  Internet using a proxy gateway for services. The program might report
              issues in hosts using proxies  even  when  these  might  connect  to  the  Internet
              properly through proxied services.

              *  Firewall environments: some of the tests rely on direct connectivity to external
              hosts, which are tested using ICMP queries (through the use of  ping.  These  tests
              might  fail in hosts installed in networking environments with firewalls that block
              outbound ICMP communication.


       ip (8), netstat (8), ifconfig (8), ethtool (8), mii-tool (8), ping (8), nc (1), curl  (1),
       and host (1).


       network-test   was   written   by  Javier  Fernandez-Sanguino  for  the  Debian  GNU/Linux


       Copyright (C) 2005-2014 Javier Fernandez-Sanguino <>.

       This program is free software; you can redistribute it and/or modify it under the terms of
       the  GNU  General  Public  License  as  published  by the Free Software Foundation; either
       version 2, or (at your option) any later version.

       On  Debian  systems,  a  copy  of  the  GNU  General  Public  License  may  be  found   in